Electrodeposition of nickel from an acid bath



\ bath.

tacked Apr. 24,195i

UNITED STATE s ,IPATEQNT oFFICE.

ELECTBODEPO SITION OF NI ICKEL Henry Brown,

Udylite Corporation,

tion of Delaware ACID BATH Detroit, Mich., assignor to The Detroit, Mich., a corpora No Drawing. Application April 20, 1946, Serial No. 663,757

,2 Claims. (01. 204-49) -'This invention relatesto the electrodeposition of bright ductile plate from aqueous acidic nickel baths.

This object can be accomplished by the addi- 7 While the alpha orbeta unsaturated aliphatic sulfonic acids such as those listed in Table III (see application Serial No. 603,753, now Patent No. 2,523,190) produce bright plate on buffed surfaces, the rate of brightening of a dull surface is rather slow, that'is, they do not improve I the brightness of the original surface at a very rapid rate. If, however, one or more of the active unsaturated compounds listed in Table I is added to the acidic nickel bath containing, for example, vinyl or allyl sulfonate, then the brightness and the rate of brightening is greatly improved.

' The compounds of Table III have no upper limit in concentration except their solubility in the After the optimum concentration is reached (usually from 1-5 g./l.), further additions produce little further improvement. Concentrations as low as 0.1 g./l. make noticeable improvement of the lower current density areas. With respect to their ability of keeping the lowest current density areas-bright and adherent despite the presence of appreciable amounts of zinc, the vinyl andallyl sulfonic acids are quite remarkable.

Thecompounds of Table I are preferably used at their optimum concentrations, though higher concentrations can be used, for example, if the bath is used at the lower temperatures such as room temperature. In general, the higher the temperature, and the greater the degree ofagitation at the cathode surface,

the smaller the concentration of the compounds of Table I for optimum results. To obtain a desirable bright plate, one or more of the compounds of Table I prefer ably is used in an amount falling within a range I from about .001 gram per liter to about .02 gram per liter of solution with one or more of the compounds of Table 111, but excessively high concentrations will produce brittleness. The compounds of Table I should not be used in concentrations above about .02 g./l. or else the plate will be made brittle. Also, it is preferred that the N-alkyl chain be less than about 8 carbon atoms or it will confer upon the compounds the properties of cationic wetting agents which will then cancel out or agglomerate with any anionic wetting agents that may be present for the prevention of pitting. In particular the N- methyl chloracetate or N-ethyl chloracetate (or the betaine form) are desirable (Nos. 11, 12) as they are the least critical to obtain the highest brightness without serious embrittlement or darkening of the lowest current density areas. Compounds Nos. 1, 2, 6, 11 and 12 are the best members to use of Table I, from the standpoint of excellent effectiveness and ,least difficulty of preparation. l

The compoundsqof Table III areremarkable in their making possible the use of higher concentrations of the compounds of Table I in the baths Without seriously impairing the ductility, besides making very bright plate possible. Even the very lowest current density'areas are made bright by the use of compounds of Table III.

TABLE I C m- Opt. Cone. pound in Bath, No. g.ll.

1 N-ethanol (B-hydroxy ethyl), 4-nitro-5-(-3' pyridimum) pyrazole chloride 0. 002-.008

c1 01114011, B E i 2 6' 13' H 2 N-ethanol, 3-nitro-5-(-3 pyridinium) yrazole chloride i 0. 002-.008 3 N-ethanol 3,441 mtro-5-(-3 pyridinium) pyrazolephlonde 0. 002-.008. 4 N-B,a, lihyd.roxy propyl-4 Intro-5 3- pyridimum) pyrazolc chloride 0. 002-.008 5 N-acetony1- 4 n1tro-5-(-3 pyridinium) pyrazole chloride 0. 002-.008 6 N-allyll nitro-5-(-3-pyridinium) pyrazole bromide; 0. 002-008 7 N-butano1-4 nitro-5-(-3-pyridinium) pyrazole iodide 0.002.008 8 N-ethyl-5-(-,3-py ndini um) pyrazole sulfate. 0. 002-.008

N-ethanol-S-(-3-isoqu1no11mum) pyrazole chloride 0. 002-.008

l0 N-ethanol-l-(-2-quinolinium) pyrazole chloride 00021008 11 N-methyl or ethyl acetate-4- 5-(-3- pyrldmium) pyrazole chlorlde 0. 002-.008 l2 N-aeetic acid (or betaine iorm)-4-nitro-5(-3- pyridinium) pyrazole chloride 0. 002-.008

TABLE II N'SO .6H 0, NiCl .BH i emp. ensi y Bath 1 gf/l. 2 g Jl. 2 g./l. F. DE A Amps. pe'r Formula g./l. sq. ft

Alpha and beta unsaturated aliphatic sulfom'c v acids V 1 CH=0-SO2OH Ni, Co, Na, K, or Mg salt) 1-8 (vinyl sulfonic acid) 2 CH2=-S 020E (Ni, on, Na, K, or Mg salt) 1-s 3 QHz-=-$ OaOH (Ni, Co, Na, K, or Mg salt) l-8 H H i 4 OH2=E( JS OZOH (Ni, Co, Na, K, or Mg salt) 1-8 (allyl sulfonic acid) 7 c1 c1 g 5 cmQJ--s 020B (Ni, 00, Na, K, or M salt) l-6 1 H H s -0=$SOOH (Ni, 00, Na, K, or Mg salt) 1-8 The best buffer to use is boric acid, though other bufiers such as citrates or formates may be used. If the latter are used, it is preferable to also use borica cid with them.

The nickel baths may contain as much as about 75-100 g./l. of COCl2. 6H2O (or its equivalent as sulfate), or about -g./1; of FeClzAHzO (or its equivalent as sulfate), andthe plates obtained are still very bright and ductile. Higher concentrations of cobalt will tend to dull the plate if-the baths are used too hot and in the case offiron, higher concentrations will tend to dull. and embrittle the plate. 7

'Besides the nickelsalts listed in Table II, other nickel salts such as nickel sulfamate may be used. In fact, any acidic nickel bath may be used for the purpose of this invention which is capable of producing thick, adherent, and preferably ductile nickel deposits without the compounds of Tables I and The best pH values to use are usually about 3-5, though higher or lower values may be used. At room temperaturesthe higher pH values are usually used. The preferred temperature is from about 122-140 F. Too low pH (below 2.0) tends to slow the. rate of brightening.

In Examples A; B, and C are listed some preferred formulations. It is noteworthy that it is possible to obtain very ductile bright plate from the baths containing high nickelchloride concentrations (overabout 125 g./l. NiC12.6H2O concentrations) with the use of the vinyl and allyl type unsaturated aliphatic sulfonic acids., No lead heatingcoilor lead-lined equipment can be used-with thehigh chloride- (and low sulfate) die-cast, Where it is baths because of the ready solubility of lead in such baths.

Example A G./L. Nickel sulfate 200-300 Nickel chloride 30-75 Boric acid 30-40 Allyl sulfonic acid (Na, K, or Ni salt) 1-3 N methylacetate 4 nitro 5( 3'- pyridinium) pyrazole chloride 0.002-004 pH=2.5-5 Temperature 122-140 F. C. D.=10-60 amps/ft? Example B G./L. Nickel chloride -250 Nickel sulfate 50-150 Boric acid 30-40 Allyl sulfonic acid (Na, K, or Ni salt) 1-4 N-allyl--nitro 5( 3 pyridinium) pyrazole bromide 0.002-004 pH=2.5-5 Temperature 122-14093. C. D.='10-100 amps/ft.

Example 0 G./L. Nickel sulfate 100-200 Nickel chloride 200-100 Boric acid 30-40 Vinyl sulfonic acid (Na, K, or-Ni salt) 1-4 N methylacetate 4 nitro 5( 3- pyridinium) pyrazole chloride 0.002-004 pH=2.5-5 Temperature 122-1 10 F. C. D.=10-100 amps/ft? Due to the. presence of the vinyl, or. allyl sulfonates the above baths tolerate exceptional amounts of zinc without getting dark streaks in the low current density ar eas:0r excessive brittleness, therefore they are highly recommended for the nickel plating of copper plated zinc base I almost impossible to prevent contaminating thebaths with zinc. It is worthwhile to note thatfthei high chloride. nickel baths (low sulfate) tolerate larger concentrations of zinc than do, the high sulfate or Watts type baths.

Theabove bright plating baths are remarkably free from pitting.

The compounds of Table I have, a relatively short life in the bath during electrodeposition as compared to the compounds of Table III. Therefore, their concentration should be checked more often and their concentration maintained on an ampere-hour basis and preferably by analysis.

Instead of the sulfonic acids of Table III. (or their Na, K, Mg; Ni, Co, Fe, etc.- salts), the alpha or beta unsaturated aliphatic sulfonam'ides and sulfonimides (such, e. g., as the allyl or vinyl sulfonamides or sulfonimides) may be used. These compounds show beneficial effects in concentrations as low as .1 g./l. and can be used efiectively in concentrations as high as saturation in the bath.

I claim:

1. A bath for electrodepositing bright nickel consisting essentially of an aqueous acid solution of amaterial selected from the group consisting of nickel chloride, nickel sulfate, a mixture of nickel sulfate and nickel chloride, a mixture of nickel fiuoborate and nickel chloride, 9. mixture of nickel fluoborate and nickel sulfate, and a mixture of nickel sulfate, nickel chloride, and nickel fiuoborate, said solution also containing in a concentration falling within a range of from about .1 gram per liter to saturation an organic compound soluble in the solution and selected from the group consisting of allyl sulfonic acids, allyl and vinyl sulfonamides and sulfom'mides, said solution also containing in a concentration falling within a range of from about .001 gram per liter to .02 gram per liter a compound selected from the group consisting of N-aliphatic pyridinium pyrazoles and N-aliphatic quinolinium pyrazoles, theN-aliphatic group containing from 1 to 8 carbon atoms, said bath having a pH of from about 1 to 6.

2. The method of electrodepositing bright nickel comprising the step of electrodepositing bright nickel from an aqueous acid solution of a material selected from the group consisting essentially of nickel chloride, nickel sulfate, a mixture of nickel sulfate and nickel chloride, a mix ture of nickel fluoborate and nickel chloride, a mixture of nickel fluoborate and nickel sulfate, and a mixture of nickel sulfate, nickel chloride, and nickel fiuoborate, said solution also containing in a concentration falling within a range of from about .1 gram per liter to saturation an organic compound soluble in the solution and selected from the group consisting of allyl sulfonic acids, allyl and vinyl sulfonamides and sulionimides, said solution also containin in a concentration falling within a range of from about .001 gram per liter to .02 gram per liter a compound selected from the group consisting of N-aliphatic pyridinium pyrazoles and N-aliphatic quinolinium pyrazoles, the N-aliphatic group containing from 1 to 8 carbon atoms, said bath having a pH of from about 1 to 6.

HENRY BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Metal Industry, Nov. 24, 1944, p. 331.

Modern Electroplating, published by Electrochemical Society (1942) pp. 242, 243.

Davis et al.: Ind. and Eng. Chem., vol. 33, pp. 1546 and 1547 (1941).

Organic Chemistry by Frank C. Whitmore, 1937, D. Van Nostrand 00., N. Y., pp. 902, 941, 943, 944, 948, 951, 952. 

1. A BATH FOR ELECTRODEPOSITING BRIGHT NICKEL CONSISTING ESSENTIALLY OF AN AQUEOUS ACID SOLUTION OF A MATERIAL SELECTED FROM THE GROUP CONSISTING OF NICKEL CHLORIDE, NICKEL SULFATE, A MIXTURE OF NICKEL SULFATE AND NICKEL CHLORIDE, A MIXTURE OF NICKEL FLUOBORATE AND NICKEL CHLORIDE, A MIXTURE OF NICKEL FLUOBORATE AND NICKEL SULFATE, AND A MIXTURE OF NICKEL SULFATE, NICKEL CHLORIDE, AND NICKEL FLUOBORATE, SAID SOLUTION ALSO CONTAINING IN A CONCENTRATION FALLING WITHIN A RANGE OF FORM ABOUT .1 GRAM PER LITER TO SATURATION AN ORGANIC COMPOUND SOLUBLE IN THE SOLUTION SELECTED FROM THE GROUP CONSISTING OF ALLYL SULFONIC ACIDS, ALLYL AND VINYL SULFONAMIDES AND SULFONIMIDES, SAID SOLUTION ALSO CONTAINING IN A CONCENTATION FALLING WITHIN A RANGE OF FROM ABOUT .001 GRAM PER LITER TO .02 GRAM PER LITER A COMPOUND SELECTED FROM THE GROUP CONSISTING OF N-ALIPHATIC PYRIDINIUM PYRAZOLES AND N-ALIPHATIC QUINOLINIUM PYRAZOLES, THE N-ALIPAHTIC GROUP CONTAINING FROM 1 TO 8 CARBON ATOMS, SAID BATH HAVING A PH OF FROM AOUT 1 TO
 6. 